The generic delimitation of Lachnaea and Cryptadenia ( Thymelaeaceae )

The current generic delimitation of Lachnaea L. and Cryptadenia Meisn. was investigated. A multidisciplinary approach was followed. This included a study of the habit, phyllotaxis, morphology and anatomy of the leaves and flowers, pollen morphology and karyology. No major differences were found between the two genera. The range of variation of certain diagnostic characters of these genera is such that the genera merge into each other. It was concluded that the two genera are congeneric and the inclusion of Cryptadenia within Lachnaea is proposed.


INTRODUCTION
The genera Lachnaea L. and Cryptadenia Meisn.belong to the family Thymelaeaceae.Their close affinity is reflected by their placement in the different classifica tion systems of the Thymelaeaceae (Endlicher 1847, sec.Domke 1934;Meisner 1857;Bentham & Hooker 1880;Gilg 1894 andDomke 1934).Only Baillon (1880) did not recognize Cryptadenia as a separate genus but treated it as a section of Lachnaea.He found that the flowers of Lachnaea varied from regular to irregular and that inter mediate forms made it impossible to split the genus.
The genus Ixichruiea.based on two species, was es tablished by Linnaeus in 1753.In subsequent publications, such as Lamarck (1792,1804), Salisbury (1808) and Sims (1813Sims ( , 1814)), new species were described, but only in 1840 was a detailed taxonomic account of the genus pub lished by Meisner based on Drege's collections.Three sec tions were established, namely Sphaeroclinium Meisn., Conocliniunt Meisn.and Micnoclinium Meisn., based on the inflorescence structure.Thirteen species and six in fraspecific taxa were recognized (M eisner 1840).Meisner's earlier contribution on Lachnaea, with some alterations, was published in De Candolle's Prodromus in which 18 species and 17 infraspecific taxa were recog nized (Meisner 1857).The most recent taxonomic treat ment of the genus was that of Wright (1915) in Flora capensis.In this treatment no mention was made of the sections established by Meisner. Wright (1915) recognized 19 species and eight infraspecific taxa, and referred to one imperfectly known species.In the Addenda to the same volume, a further two species and two infraspecific taxa were added (Wright 1925).Since then four new species have been described, namely three by Compton (1934aCompton ( & b, 1953) ) and one by Fourcade (1934).When Thoday (1924) published the revision of the genus Passerina, he noted that the type of Passerina laniflora C.H. Wright was not a Passerina species but indeed a species of Lach naea.Bond (1982) proposed the new combination, Lach naea laniflora (C.H. Wright) Bond.L. marlothii Schltr.(Schlechter 1896) and L gracilis Meisn.(Meisner 1840) were both overlooked by Wright.At present 29 species and eight infraspecific taxa are recognized (Van Wyk 1993).
The genus Cryptadenia, comprising five species, was established by Meisner in 1840 and was also based on Drege's collections (Meisner 1840).According to Meisner (1840) the main characters by which Cryptadenia can be distinguished from the closely related genus Lachnaea, are the glands which are positioned much lower down in the hypanthium just above the ovary, and by the con spicuous filaments which are adnate to the hypanthium.In De Candolle's Prodromus the same five species were recognized by Meisner (1857).The most recent taxonomic treatment of Cryptadenia was that of Wright (1915) in Flora capensis, in which four of the species in Meisner's treatment were recognised, whereas one was reduced to synonymy.A new species was also described.The criterion used by Wright (1915) to delimit the two genera was the position of the flowers: 'Flowers axillary, solitary'' in Cryptadenia opposed to 'Flowers terminal, capitate, rarely solitary' in Lachnaea.At present Cryptadenia is considered to comprise five species (Van Wyk 1993).
Both Lachnaea and Cryptadenia are endemic to the Cape Province.Lachnaea is found mainly at high altitudes from Clanwilliam in the north to the Cape Peninsula in the south and eastwards along the coastal areas as far as Uitenhage.Further inland it occurs on the mountain ran ges from Ceres through Worcester to Ladismith (Bond & Goldblatt 1984).The centre of diversity is in the south western area.Cryptadenia occurs on sandy flats and lower mountain slopes from Piketberg in the west to the Cape Peninsula, and along the coastal areas to Bredasdorp and inland to Ceres (Bond & Goldblatt 1984).
Lachnaea and its closest related genus, Cryptadenia, are both characterized by the absence of petals and by a hypanthium having scales below the insertion of the stamens.Beyers & Van der Walt (1994), contrary to Wright (1915), found that the two genera could not be distinguished on the inflorescence structure.With the large number of herbarium specimens now available, compared to the small range of material on which earlier studies were based, a sound delimitation of the two genera is possible.The aim of the present investigation was to com pare the two genera using a multidisciplinary approach, with the view to establishing whether they are congeneric or not.Besides the morphological study accompanied by field work, anatomical, palynological and karyological in vestigations were undertaken to assess the taxonomic value of the evidence derived from these sources.

MATERIALS AND METHODS
Eighteen taxa were selected, 14 from Lachnaea and four from Cryptadenia.The aim in selecting the taxa was to have as broad a representation as possible of all the taxa in the two genera.The criteria used for selecting the Lachnaea taxa were as follows: a, taxa representative of the three sections instituted by Meisner (1840).taking into account the variation in each section; b. all taxa with solitary flowers; c, the position of the scales in the floral tube; d, the stigma types; e, the degree of asymmetry of the calyx lobes.
Wright's revision of Lachnaea and Cryptadenia in Flora capensis (1915 and 1925) was followed.Type specimens and quoted specimens were examined to verify the species concepts for the taxa used in this study.In fraspecific variation has been included in each taxon studied and has not been treated individually.
Four of the five species of Cryptadenia currently recognized were studied.Cryptadenia breviflora Meisn.was excluded as it is an intermediate taxon between Cryp tadenia grandiflora (L.f.) M eisn.and Cryptadenia uniflora Meisn., which Levyns (1950) considered to be a hybrid between these two species.
For the anatomical study of the foliage leaves, both material preserved in FAA and herbarium material was used.The herbarium material was soaked in 50% ethanol for 24 hours, thereafter treated as preserved material.The preserved material was dehydrated and embedded in wax according to the tertiary butyl method (Johansen 1940).Transverse sections 12 |im thick were made through the middle ot the leaf blade with the aid of a rotary microtome and stained with Alcian Green Safranin (AGS) (Joel 1983).Scanning electron micrographs of the leaf surfaces were obtained by mounting portions from the same region of the leaf blade of herbarium material on stubs which were coated with gold and studied with a Joel JSM-35 scanning electron microscope.Epidermal cell patterns of the leaf blade were studied under a light microscope after the adaxial and abaxial epidermal layers were peeled off and mounted in water.
The anatomical study of the flowers was done on material preserved in FAA.The preserved material was dehydrated and embedded in wax according to the tertiary butyl method (Johansen 1940).For the anatomy, transverse each genus.The terminology used to describe the pollen morphology is that of Walker & Doyle (1975).
For chromosome studies inflorescences were fixed in Camoy's fixative in the field.After 24 hours, the fixative was replaced with 85% ethanol for 15 minutes and then finally replaced with 70% ethanol.Flower buds were stained in Snow's fluid (1963).The anthers were removed and squashed in 45% acetic acid.
Voucher specimens for the anatomy of leaves and flowers and for pollen morphology and karyology are given in Tables 1 and 2.

Habit
I n Lachnaea the species are sparsely to densely branched, erect shrubs or erect to sprawling shrublets 0.15-2.00m high.There is considerable variation in ap pearance and size among, and sometimes within species.The Cryptadenia species are erect or sprawling, moderate ly to densely branched shrublets 0.12-0.80m high.In both genera the species are either basally single-stemmed, multi-stemmed, or single-stemmed and multi-stemmed within a single species.The branches are leafy, usually with an adpressed pubescence, later becoming naked and glabrous, and usually marked with the leaf scars of the fallen leaves.

Morphology of foliage leaves
In Lachnaea the leaves are alternate or decussate, but in L hurchellii they are opposite or subopposite and in L diosmoides they are alternate to subopposite.The leaves are adpressed, ascending, patent or occasionally reflexed, and imbricate to scattered.The leaves in Cryptadenia are decussate, adpressed.ascending or sub-patent, and imbri cate or scattered.In both genera the orientation and posi tion of the leaves on the axis may vary inter-and intraspecifically.
sections were used almost exclusively and longitudinal sections were resorted to only to verify the points of at tachment of the floral structures.Serial sections were cut 12 jim in thickness.AGS staining (Joel 1983) as well as Crystal Violet and Erythrosin staining (Jackson 1926) were used.The AGS staining technique was found to give better results.
Pollen was taken from herbarium specimens and from material collected in the wild.For both light microscopy (LM) and scanning electron microscopy (SEM), pollen was acetolyzed according to Erdtman (1960).Acetolyzed samples were prepared for both SEM and LM according to the method of Marais (1990).At least 20 pollen grains of each taxon were measured.Transverse sections ± 15 jam thick were made with the aid of a freeze-microtome to study the structure of the pollen wall of iwo taxa in The leaves in both genera are always entire and usually sessile except in L ruscifolia where they may be subpetiolate.The shape of the leaves in Lachnaea can be linear-elliptic to elliptic, oblanceolate, obovate or ovate (Figures 1, 2).Again, the variability is not only among the species but may be within a particular species (Figure 2).The leaves range in size from 2-34 x 0.6-9.0mm.Within some species, as in L filamentosa (Figure 2), the variation in leaf size may be considerable, namely from 5-34 x 1.8-12.0mm.In Cryptadenia the shape of the leaves can be lanceolate, narrowly elliptic, narrowly ovate or obovate.In C. uniflora the leaves are always narrowly elliptic but in C. grandiflora they are narrowly elliptic, narrowly obovate, obovate or oblanceolate.As in Lach naea the shape and size of the leaves vary inter-and intraspecifically (Figure 3).The range in leaf size is 2.9-12.8x 0.6-3.2mm.The leaves in both genera are coriaceous but in L densiflora they are occasionally semi succulent.
In Lachnaea the abaxial side of the leaves may be flat, obtusely convex to convex, or faintly keeled or keeled in the distal half.Adaxially they may be flat, obtusely con cave or concave.Both surfaces of the leaves are usually smooth.However, the abaxial surface in L ruscifolia and L nervosa has several longitudinal ribs, whereas in L diosmoides there is only a single midrib.The abaxial sur face is usually green and shiny, whereas the adaxial sur face is usually pale green, dull and white-punctulate but in some species the leaves are concolorous.The con-  keeled or keeled, smooth or transversely rugulose towards the margins with a shiny, green surface, whereas adaxially they are concave with a smooth, dull, pale green, whitepunctulate surface.
In Lachnaea the leaves are glabrous or pubescent at the margins but the marginal pubescence is often deciduous, whereas in Cryptadenia the leaves are always glabrous.

Anatomy of foliage leaves
In transverse sections the leaves of most Lachnaea species and all Cryptadenia species appear concave adaxially and convex abaxially (Figure 4A, D, E), but in L densiflora both surfaces are flat or the adaxial one may be slightly convex (Figure 4B); in L huxifolia (Figure 4C) and L filamentosa both surfaces are flat.

Cuticle
In Lachnaea the cuticle is well developed and of even thickness on both sides, or thicker on the abaxial side, whereas in Cryptadenia the well-developed cuticle is al ways thicker abaxially.Under the SEM the adaxial and abaxial cuticles of the Lachnaea species are unsculptured (Figure 5 A, D), undulate (Figure 5B, E) or minutely papillate (Figure 5C, F).In Cryptadenia the cuticle is usually minutely papillate adaxially, as in C. grandiflora (Figure 6A), but in C. filicaulis it is unsculptured (Figure 6B).The relief of the abaxial cuticle is either minutely papillate (Figure 6C) or undulate (Figure 6D).In C. grandiflora, however, both types of cuticular sculpturing occur abaxially.
Waxes in the form of small flakes occur commonly on the adaxial leaf surfaces of Cryptadenia species and most Lachnaea species (Figure 7 A, C).In both genera, when waxes are present on the abaxial surface, they are sparse and flakelike (Figure 7B, D).Cutter (1978) is of the opinion that it is this wax deposit that gives the 'bloom' to glaucous leaves.
Trichomes, when present, are non-glandular and uniseriate in both genera.

Epidermis
In both genera the adaxial epidermis is composed of small cells with thin anticlinal and inner tangential walls and slightly thicker outer tangential cell walls.In L eriocephala the outer tangential cell walls are the thickest (Figure 4A).In Lachnaea and Cryptadenia the adaxial epidermis is uniseriate as in L. eriocephala (Figure 4A) and C. grandiflora (Figure 8D, E), incompletely uniseriate (occasional cells with periclinal walls) as in L ericoides (Figure 8A) and C. uniflora (Figure 8C), incompletely biseriate (occasional cells without periclinal walls) as in L densiflora (Figure 4B) and G laxa (Figure 4E) or biseriate as in L. buxifolia (Figure 4C).The abaxial epider mis is usually biseriate in both genera.However, in L axillaris and L ericoides (Figure 8A) it is incompletely biseriate and in G grandiflora it may be uniseriate (Figure 8D) or incompletely biseriate (Figure 8E).
When the epidermis is biseriate, the cells of the inner layer are usually larger than those of the outer layer.The epidermis contains mucilage, except in G grandiflora where it was not always observed.The mucilage may be present in the cells of the inner and outer epidermal layers, or in the cells of the inner layer only.
Druse crystals were observed in the epidermis of L buxifolia, L filamentosa and L ruscifolia, and sometimes in the adaxial epidermis of G grandiflora.

Stomata
The stomata in both genera are anomocytic and sunken except in L. funicaulis and L penicillata where they are on the same level as the outer walls of the surrounding epidermal cells.In Lachnaea the leaves are epistomatic or amphistomatic but in Cryptadenia they are only episto matic.When the leaves are amphistomatic, there are usually more stomata adaxially.

Mesophyll
In both genera the cells of the m esophyll are chlorenchymatous and palisade-like (elongated perpen dicular to the axis) with the exception of C. grandiflora where they are either palisade-like (Figure 8E) or short and more or less round (Figure 8D).As a result of the size of the intercellular spaces, the leaves can be classified as dorsiventral or isobilateral.When dorsiventral, the smaller intercellular spaces occur abaxially and the larger ones adaxially as in L axillaris, L diosmoides (Figure 8B), L ericoides, L eriocepluila, L funicaulis, L nen osa, L penicillata, C.filicaulis, C. laxa and C. uniflora (Figure 8C).The isobilateral arrangement occurs in L aurea, L bunhe 11ii, L buxifolia, L capitata, L densiflora (Figure 4B), L filamentosa and L ruscifolia.In G grandiflora however, a dorsiventral or an almost isobilateral arrange ment is found.
Tannin occurs in the parenchymatous cells surrounding the median vascular bundle in L penicillata and some times in the mesophyll in C. grandiflora.
Druse crystals are present in the mesophyll of L. aurea, L axillaris, L. burchellii, L. buxifolia, L. capitata, L densiflora, L filamentosa, L nervosa and the four Cryptadenia species, and in the vascular tissue of L filamentosa.

Venation and vascular bundles
The venation in both genera is reticulate and the vas cular bundles are collateral.As Metcalfe & Chalk (1950) stated, no internal phloem occurs in the midrib.
In both genera, extraxylary fibres occur abaxially in association with the vascular bundles.A prominent median fibre strand (Figure 8) is present in all the species except in L. buxifolia and L. filamentosa.In addition to the prominent median fibre strand, equally prominent fibre strands occur in association with the larger lateral vascular bundles in L nervosa, L ruscifolia and C. grandiflora (Figure 8E).In L. ruscifolia the median and larger lateral strands extend to the abaxial epidermis.
Extraxylary fibres not associated with the vascular bundles, occur along the lateral margins immediately below the epidermis in L. aurea (Figure 8F).

Pedicel/floral articulation
The flowers in Lachnaea are either sessile or shortly pedicellate with pedicels up to 2.5 mm long.In Cryp tadenia the flowers are always sessile.In L eriocephala, L funicaulis and L penicillata the sericeous to villous pedicels elongate in the fruiting stage and remain on the plant long after the fruit has been shed.These hairy pedicels are responsible for the woolly appearance of the old inflorescences.The flowers of Lachnaea and Cryp tadenia are at their bases surrounded by a ring of trichomes, which occurs at the floral articulation of the sessile flowers or on the pedicels.

Hypanthium
In Lachnaea the basal portion of the hypanthium is ellipsoid to widely ellipsoid, ovoid to widely ovoid, or obovoid, whereas the portion above the plane of circumscision is funnel-shaped, cylindrical, obconical, cup shaped or cup-shaped with a sigmoid curve at the base (Figure 9).In Cryptadenia the basal portion of the hypan- thium is ovoid or ellipsoid, whereas the upper portion above the plane of circumscision is funnel-shaped or cup shaped (Figure 9).The position of the plane of circum scision, expressed as a percentage of the length of the base to the total length of the hypanthium, varies from 20-80% in both genera.The upper portion of the hypan thium abscises soon after seedset at the plane of cir cumscision.The length of the hypanthium ranges from 1.5-17.5 mm in Lachnaea and from 2.2-11.0mm in Cryptadenia.
The outer surface of the base of the hypanthium is pubescent or glabrous in Lachnaea and pubescent in Cryptadenia, whereas the inner surface is usually glabrous in both genera, except in L buxifolia and C. uniflora where it is pubescent.The outer and inner surfaces of the upper portion of the hypanthium in both genera are usual ly pubescent, but in L axillaris the outer surface is glabrous.
In both genera the shape of the trichomes and type of pubescence on the outer surface of the hypanthium often changes around the plane of circumscision.In L bunchellii the trichomes on the basal portion are clavate, whereas those on the upper portion are longer and acicular (Figure 10).In C. laxa the trichomes of the basal portion are ob tuse, whereas those of the upper portion are acicular.The pubescence on the outer surface of the hypanthium is denser in the vicinity of the scales in both Lachnaea and Cryptadenia.The upper portion of the hypanthium and the calyx are concolorous.

Calyx
The calyx in both genera comprises four sepals which are fused to the rim of the hypanthium.In Lachnaea the sepals vary from being almost equal to distinctly unequal, but with a gradual transition from one form to the other (Figure 11).In the distinctly zygomorphic forms the anterior lobe is usually the longest The sepals are narrowly to widely elliptic, ovate to widely ovate, or obovate to widely obovate.The size of the anterior sepal ranges from 1.3-22.0x 0.8-7.5 mm, that of the two lateral sepals from 1.3-7.5 x 0.6-4.5 mm, and that of the posterior sepal from 1.2-5.5 x 0.7-3.5 mm.Because the flowers of L axillaris and L ruscifolia are solitary, the outer sepals represent the posterior and anterior sepals and the two inner sepals represent the two lateral sepals.The abaxial surface of the sepals is pubescent, except in L axillaris where it is glabrous.The adaxial surface of the sepals is usually pubescent, but in L aurea and L nervosa it is glabrous and in L axillaris and L funicaulis it is partly glabrous and partly pubescent.The calyx is white, cream, pink, pale blue, white or cream tinged with pink or blue, or yellow.
The sepals in Cryptadenia are almost equal (Figure 12), narrowly to widely elliptic, ovate or orbicular, varying in size from 1.6-10.7 x 1.2-5.8mm with the apices acute, rounded or obtuse.The abaxial surface is pubescent whereas the adaxial surfacc is cither glabrous or pubes* cent.The calyx is white, cream, white tinged with pink, pink or mauve-pink.
The aestivation of the sepals is decussate-imbricate in Lachnaea and Cryptadenia.

Petals
Petals are absent in all taxa.

Androecium
Eight stamens in two whorls of four are present in all laxa.In Lachnaea the outer whorl, the antisepalous stamens, are episepalous, inserted on the basal portion of the sepals, or they are inserted on the rim of the hypan thium (Figure 11).The stamens of the inner whorl, the antipetalous stamens, are inserted on or very close to the rim of the hypanthium or a third of the way down the throat of the upper portion of the hypanthium as in L capitata (Figure 1

IF).
In Cryptadenia the outer whorl, the antisepalous stamens, are episepalous, fused to the basal portion of the sepals as in C. grandiflora and C. laxa, or inserted in the upper throat of the hypanthium as in C. uniflora and C. filicaulis (Figure 12).The inner whorl, the antipetalous stamens, are inserted at the rim of the hypanthium in C. laxa, a quarter of the way down in the upper portion of the hypanthium in C. uniflora and a third of the way down in C. filicaulis and C. grandiflora (Figure 12).The stamens are fully exserted in Lachnaea (Figure 11).In Cryptadenia the antisepalous stamens of all the taxa and the antipetalous stamens of C. laxa are exserted.In the other Cryptadenia species only the anthers of the antipetalous stamens are exserted or semi-exserted (Figure 12).The anthers are basifixed and introrse.In Lachnaea they are either spherical or oblate-spherical, whereas in Cryptadenia they are ellipsoid or ovoid.

Scales
Eight scales are inserted on the upper portion of the hypanthium below the attachment of the antipetalous stamens and alternating with the stamens.The position of the scales varies in different species of both genera.In most Lachnaea species the scales are inserted at the mouth of the hypanthium but in some species they are inserted two thirds or halfway down the upper portion of the hypanthium (Figure 11).In Cryptadenia they are inserted either at the mouth of the hypanthium or midway to three quarters of the way down the upper portion of the hypanthium (Figure 12).
The shape of the scales varies in the different taxa.They can be linear, clavate, subrotund, capitate, ovoid or obovoid in Lachnaea, whereas in Cryptadenia they are subrotund, narrowly oblong, oblong or ellipsoid.In both genera the scales are either translucent-white or yellow.They are usually glabrous, except in L buxifolia where they have long stiff trichomes at their apices.In all the Lachnaea species and in C. laxa the scales are basally attached to the hypanthium.In C. filicaulis the scales are basally and partly abaxially attached to the hypanthium, and in C. grandiflora and C. uniflora they are abaxially attached to the hypanthium.

Disc
A disc is absent in both genera.

Gynoecium
In Lachnaea the ovary is sessile, oblong, narrowly el lipsoid, ellipsoid, ovoid or obovoid, 0.5-4.4x 0.2-2.5 mm, completely glabrous or glabrous with a tuft of hairs at the apex.In L filamentosa the ovary is usually glabrous with a tuft of hairs at the apex but occasionally it may also be adpressed hairy and tufted at the apex.
In Cryptadenia the ovary is sessile, ellipsoid, 0.7-1.8x 0.4-0.7 mm.usually glabrous, but in C. filicaulis it is glabrous or pubescent towards the apex on the side where the style is inserted.
In both genera the ovary is unilocular, with a solitary anatropous ovule laterally attached near the top of the ovary; the style is laterally attached, linear or linear-obconical.The style is either completely glabrous or pubes cent in the distal third to two thirds, or completely pubescent in Lachnaea, whereas in Cryptadenia it is usually glabrous but in C. laxa the distal half is pubescent.

Fruit
The fruit in both genera is an achene which is enclosed in the persistent base of the hypanthium.The pericarp is dry and thin, whereas the seed coat is thick and crustaceous.

Vascular anatomy o f the flower
The basic vascular pattern is the same in both genera.The eight traces supplying the calyx, depart from the vas cular tissue of the pedicel or the floral axis, where they are arranged in a continuous cylinder (Figure 14A) or in a ring of bundles (Figure 15 A) in Lachnaea and in a con tinuous cylinder in Cryptadenia (Figure 16A).The eight sepal traces extend upwards in the hypanthium.The lateral bundles of the sepals arise commissurally after the depar ture of the antipetalous stamen traces (Figure 17A, C, G,  H, I) or at the same point of departure of the antipetalous stamen traces (Figure 17B, D, E, F, J) at various levels on the hypanthium.The vascular supply of the sepals con sists of a midrib bundle and two lateral bundles.
The stamens are single-trace organs.The antipetalous stamen traces are fused to the commissural sepal traces, and the antisepalous stamen traces to the sepal midrib traces at their point of origin from the stele.The stamen traces separate from the sepal traces in two whorls at dif ferent levels in the hypanthium.The antipetalous stamen traces diverge from the commissural sepal bundles before the antisepalous stamen traces diverge from the sepal midrib bundles (Figure 14).The antisepalous stamen traces leave the sepal midrib bundles at or just below the rim of the hypanthium, except in C.filicaulis (Figure 17H) where they depart a quarter of the way down the upper portion of the hypanthium.The antipetalous stamen traces leave the commissural sepal bundles at various levels on the upper portion of the hypanthium.In L buxifolia (Fig ure 17F), L diosmoides (Figure 17B), L eriocephala (Fig ure 17D), L ruscifolia (Figure 17E) and C. laxa (Figure 17J) these stamen traces depart near the rim of the tube, in L axillaris (Figure 17C), C.filicaulis (Figure 17H), C. grandiflora (Figure 171) and C. uniflora (Figure 17G) they depart midway and in L. capitata (Figure 17A) they depart three quarters of the way down the tube.The stamens become free from the hypanthium a short distance above the divergence of their traces as in L. buxifolia (Figure 17F) and C. filicaulis (Figure 17H), or are adnate to the hypanthium for some distance before becoming free as in L capitata (Figure 17A) and C. uniflora (Figure 17G).In L buxifolia (Figure 17F), L diosmoides (Figure 17B), L eriocephala (Figure 17D), C. grandiflora (Figure 171) and C. laxa (Figure 17J) the antisepalous stamens are adnate to the basal portion of the sepals.In Cryptadenia, with the exception of C. laxa, the hypanthium, above the in sertion of the scales, is further augmented by small median sepal bundles whose stelar extensions have been aborted (Figures 17G, H, I; 18A).Branches of these median sepal bundles may anastomose with the midrib bundles and the commissural sepal bundles.A rich vascular plexus exists in the hypanthium of C. laxa at the level of insertion of the scales (Figure 17J).
The eight scales arise as emergences from the adaxial wall of the hypanthium (Figure 19) at different levels on the upper portion of the hypanthium.They emerge a short distance below the divergence of the antipetalous stamen traces from the commissural sepal bundles, as in L capitata (Figure 17A) and in C. grandiflora (Figure 171), or just above the divergence of the antipetalous stamen traces and the lateral sepal traces from the commissural sepal bundles, as in L buxifolia (Figure 17F) and in C. laxa (Figure 17J).No vascular tissue is present in or at the base of the scales, even in those taxa in which the scales are inserted in close juxtaposition to the sepal lateral bundles and the sepal midrib bundles.In Lachnaea the scales are usually non-glandular (Figure 20A) but in L axillaris (Figure 20B) they are composed of compact thinwalled cells rich in cytoplasm with large nuclei, thus ap pearing glandular (Esau 1965).Similarly in Cryptadenia the scales are either non-glandular or appear glandular.No secretion was observed from the scales in either genus.
The ovary is bicarpellate.In Lachnaea the dorsal car pellary bundle of the fertile carpel is always present, whereas the dorsal carpellary bundle of the sterile carpel is present in L capitata and L. diosmoides (Figure 15), but absent in L. eriocephala (Figure 21) and L axillaris.In Cryptadenia the dorsal carpellary bundle of the fertile carpel is usually present, but absent in C. filicaulis (Figure 16) whereas the dorsal carpellary bundle of the sterile car pel is always present (Figure 16).The commissural carpellary bundles (Heinig 1951) are closely associated with the dorsal bundle of the sterile carpel (Figures 15,16), or when the latter is absent they are in the associated position (Figure 21).
The vasculature of the style is variable.It may consist of: the commissural carpellary bundles as in L diosmoides (Figure 15), L. axillaris and L capitata; the two ventral bundles of the sterile carpel arising from the split com missural carpellary bundles as in L eriocephala (Figure 21); the dorsal bundle of the fertile carpel, the dorsal bundle of the sterile and the commissural carpellary bundles as in C. grandiflora; the dorsal bundle of the sterile carpel and the commissural carpellary bundle as in C. filicaulis (Figure 16) and C. uniflora; or the dorsal bundle of the fertile carpel and the dorsal bundle of the sterile carpel as in C. laxa.crotonoid.The sexine is thicker than the nexine.The sexine is attached to the nexine by means of columellae, which unite into a tectum above.The tectum is reticulate with supratectal triangular projections.These supratectal structures are trihedral to shallowly trihedral with the basal sides straight as in L buxifolia (Figure 23A), L ruscifolia (Figure 23B) and C. uniflora (Figure 23E) or emarginate as in L aurea (Figure 23C), L eriocephala (Figure 23D) and C. laxa (Figmo 231).A vestigial spinule occurs at Pollen grains of the Lachnaea and Cryptadenia species examined, have the same basic morphology.The grains are monads, globose and polyforate (Figure 22) with a diameter of 22-52 |im in Lachnaea and 40-50 |im in Cryptadenia (Table 3).
The pollen is tectate and supra-omate (Figure 22).Erdtman (1971) describes the sculpture pattern as the base of each of the three main ridges in Lack-Cryptadenia (Table 5).The meiotic chromosome benaea species (Figure 23A, B) but was absent in all the haviour was normal.
Cryptadenia species (Table 4).The surface of the lateral sides of the supratectal trihedral projections is striate in all the species (Figure 23).

Karyology Habit, phyllotaxis and foliage
The haploid chromosome number of n = 9 was ob-The habit, phyllotaxis and macromorphological charserved in six species of Lachnaea and in two species of acters of the foliage leaves are rather variable among the   macromorphological characters of the foliage leaves no major differences were found which could be used to demarcate the two genera.
Based on the anatomy of the leaves, two leaf groups can be distinguished within Lachnaea: 1, those which are amphistomatic and either isobilateral or almost centric; 2, those which are epistomatic and either isobilateral or dorsiventral.The leaves of Cryptadenia are epistomatic and either almost isobilateral or dorsiventral.The anatomy of the latter resembles that of the second group in Lachnaea.Similar cuticular patterns, namely unsculptured, minutely papillate or undulate, occur in both genera.These charac ters confirm the close relationship between Cryptadenia and Lachnaea.

Pedicel/floral articulation
The study of the floral morphology revealed the strong similarity between Lachnaea and Cryptadenia.Sessile flowers are found in both genera.The ring of trichomes at the base of the flower, occurring at the floral articula tion, corresponds to that found by Heads (1990) in Kelleria Endl.This structure, according to Heads (1990) is reminiscent of the calycular pappus of many members of the Asteraceae and the peltate hairs of Elaeagnaceae, and could be regarded either as a compressed pubescent 'pedicel' or as the 'calyx' of a sessile flower.pedicels of pedicellate flowers of Lachnaea species are always pubescent.The trichomes at the floral articulation do not differ from those on the pedicel and it is therefore more acceptable to regard the ring of trichomes at the base of the sessile flowers as a compressed pubescent 'pedicel'.

Hypanthium
The nature of the hypanthium of the flower of the Thymelaeaceae has been interpreted as being appendicular (foliar) and representing a calyx tube by Meisner (1857), Wright (1915), Peterson (1959) and Dyer (1975), or as being receptacular by Eichler (1878), Baillon (1880), Gilg (1894), Wettstein (1935), Rendle (1938) and Bunninger (1972).According to Lawrence (1951) the hypanthium is more commonly and inaccurately termed the calyx tube or floral tube.Heads (1990), Heinig (1951) and Saunders (1939) regard the floral tube of the Thymelaeaceae as a hypanthium.The vascular anatomy undertaken in this study has shown that the floral tube in both genera can be regarded as a hypanthium.
The position of the plane of circumscision expressed as a percentage of the total length of the hypanthium varies in both genera between 20% and 80%.The shape.length and pubescence of the hypanthium of Cryptadenia falls well within the variation range found in Lachnaea.

Calyx
The sepals in Lachnaea vary from being almost equal to distinctly unequal.The transition from one form to the other is gradual.The sepals of Cryptadenia are almost equal which was one of the reasons why Baillon (1880) incorporated Cryptadenia as a section in Lachnaea.
The aestivation of the sepals is the same in both genera and a basic floral vascular pattern is common to both genera.

Androecium
Eight stamens in two whorls of four each are present in both genera.The position of insertion on the floral tube shows a varying degree of adnation within both Lachnaea and Cryptadenia.The stamens are always exserted in Lachnaea, but in Cryptadenia they are either exserted or only the antisepalous stamens are fully exserted.

Scales
In the different genera of the Thymelaeaceae organs comparable to the scales in Lachnaea and Cryptadenia have been interpreted by various authors as petaloid glands, scales, mere outgrowths of the perigynium, aborted stamens, squamellae which should be regarded either as new structures of uncertain origin or as modified parts of the androecium, stipules or petals which might be reduced or greatly modified in form (Heinig 1951).
In Lachnaea various views regarding the nature of these scales have been expressed, namely that they should be regarded as staminodes, scales, glandular or scale-like receptacular effigurations, or petaloid scales homologous to petals.In those species of Lachnaea where these struc tures are narrowly straplike filiform, Domke (1934) regarded them to be in their original form and for that reason Meisner (1840), according to Domke (1934), mis takenly considered them to be staminodes.These struc tures, in their original position according to Domke (1934), are inserted at the base of the calyx lobes and slightly higher than the insertion of the antipetalous stamens but through zygomorphy these structures have positioned themselves in a single whorl at the same height as, or sometimes below, the filament insertion.This situa tion is not met in other genera such as Gnidia and Struthiola, where the petal-like structures are inserted above the insertion of the filaments at the mouth of the tube.From the vascular anatomy of the flowers one would rather believe the converse, namely that the scales were orginally positioned below the antipetalous stamen whorl and through zygomorphy have been slightly displaced to above the antisepalous stamen insertion, as in L, filamen tosa.Heinig (1951) considered these structures to be stipules of the calyx lobes and found no reason to consider them to be vertical extensions of the disc as Gilg ( 1894) did.Taxonomists have not been eager to accept the inter pretation of the petaloid scales as stipules on the grounds that stipulate sepals would not occur in a group in which the foliage leaves are exstipulate.Heinig (1951) supported her interpretation on the grounds that the absence of stipules on the foliage leaves and the presence of stipular appendages in the floral organs should be considered another aspect of the progressive reduction from a more primitive state.Heads (1990) rejects Heinig's interpreta tion of the petaloid scales being stipules on the grounds that she used the concepts of Meat" and 'stipule' of Eames & MacDaniels (1948) which were in turn derived from Van Tieghem's (1871in Heads 1990) morphology which he regards as being fundamentally Hawed.Heads (1990) refers to the comparable organs in Kelleria as gland scales.
In Cryptadenia, as in Lachnaea, different views regard ing the scales have been expressed.They have been referred to as glands, scales, glandular or scale-like receptacular effigurations, or petaloid scales.Although Domke (1934) referred to them as 'glands', he regarded them as petaloid scales homologous to those of Lachnaea.Accord ing to Domke (1934) the 'effigurations' in L axillaris, L diosmoides and L. ericoides, because of their position and shape, lead directly to those in Cryptadenia where these structures are nearly completely attached abaxially to the hypanthium.
Because of their position and anatomy, we regard these structures in both Lachnaea and Cryptadenia.as scales which are mere emergences of the adaxial wall of the hypanthium.
The position of the scales in both genera is usually below the insertion of the antipetalous stamens.In the more zygomorphic forms in Lachnaea and in one species of Cryptadenia, where they are in close juxtaposition to the stamens, they emerge between the insertion of the an tipetalous and antisepalous stamens.The position of the scales in the upper portion of the hypanthium is variable in both genera.Those of Lachnaea are inserted at the mouth of the hypanthium to midway down the upper por tion of the hypanthium, whereas those in Cryptadenia are inserted at the mouth of the hypanthium to three quarters of the way down the upper portion of the hypanthium.On the grounds of the position of the scales, a generic character used by Meisner (1840Meisner ( . 1857)), no cutoff point can be made to separate the two genera as the displace ment of the scales is gradual.In both genera the scales may be non-glandular or glandular.Another generic char acter which Domke (1934) used, was the attachment of the scales to the hypanthium.According to him the scales in Lachnaea are basally attached, whereas those in Cryp tadenia are abaxially attached.In L axillaris the cup shaped and sigmoid basal part of the upper portion of the hypanthium gives the impression that the scales are basal ly attached.If however, the sigmoid curve is removed by extending the hypanthium upwards, the scales would in fact be abaxially attached and would correspond to the situation in the flower of C. filicaulis.

Gynoecium
The ovary in both genera is sessile, pseudomonomerous (consisting of one expanded or fertile carpel and one contracted or sterile carpel) and unilocular with a solitary anatropous ovule laterally attached near the top of the ovary.The style is always laterally attached to the ovary.The stigma is either brush-like or capitate in both genera but may also be conical in Cryptadenia.
Zygomorphy is expressed in both genera through the lateral placement of the style and the single locule.

Fruit
In both genera the fruit is an achene which is enclosed w ithin the persistent base of the hypanthium.According to Domke (1934) the achene is, without exception, char acteristic of the Thymelaeoideae and thus at the generic level the fruit is not of taxonomic importance.

Pollen morphology
The pollen grains of Lachnaea and Cryptadenia have the same basic morphology.Based on the sculpture of the supratectal structures two pollen grain types can be dis tinguished within Lachnaea.namely those with vestigial spinules at the base of the three main ridges and those without spinules.In Cryptadenia the supratectal structures are devoid of spinules at the base of the three main ridges and are thus similar to the latter pollen grain type of Lach naea.Furthermore, in both genera, the lateral sides of the trihedral structures are striate and the basal sides are either straight or emarginate.The pollen grain size, following Radford et al. (1974).is medium to large in Cryptadenia and small to large in Lachnaea.This feature, therefore, also overlaps in the two genera.
The chromosome number of Lasiosiphon eriocephaliis Decne., according to Subramanyan Kamble in Line 1967, is n = 8.The genus Lasiosiphon Fresen.was incor porated in the genus Gnidia for southern Africa (Dyer 1975).Although the above species is not indigenous to South Alrica.it was the only chromosome number pre viously available for a genus of the Thymelaeaceae repre sented in South Africa.
The chromosome counts of n = 9 here reported for the species of both Ixichnaea and Crsptadenia.aa* the first records for these two genera.The basic chromosome num ber of x = 9 was recorded for most genera of the Thymelaeaceae and can therefore not be used to demar cate senera.

CONCLUSIONS
The Thymelaeaceae is a family in which it is difficult to find sound characters for generic delimitation.Accord ing to Peterson (1959), only a few characters can be used and they are of superficial significance.While revising the thymelaeaceous genera of the African continent, Peter son (1959) experienced difficulties with the classification.According to him these difficulties were not so much con nected to the species concept but rather to the delimitation of genera which showed morphologically continuous characters which merged them into each other.
According to Baillon (1880) In evaluating the results obtained from the present mul tidisciplinary study, consideration was given to those char acters which Baillon ( 1880) advocated as being of value at generic level as well as those used by Heads (1990) to illustrate the major differences between Kellerici Endl.and Drapetes Lam.The results of this multidisciplinary ap proach, as summarized in Table 6, illustrate the great similarity between Lachnaea and Cryptadenia.These also show that several characters within Lachnaea exhibit a variation range which includes the variation in Cryp tadenia, and that in a few other characters the variation range is extended in Cryptadenia.No distinguishing char acters of generic value were found to support the present demarcation of Lachnaea and Cryptadenia.Furthermore Beyers & Van der Walt (1994) concluded that the inflores cence morphology revealed no distinct differences be tween Lachnaea and Cryptadenia.
With the view of establishing natural genera, and on the basis of the findings of this multidisciplinary study, we support the viewpoint of Baillon (1880) that Cryp tadenia should be included within Lachnaea.A detailed taxonomic treatment of Lachnaea sensu lato should now be undertaken.

FIGURE 16 .-
FIGURE 16.-Cryptadenia filicau lis, O liver 9803.A, transection through floral axis.B -D , transections o f flower: B, base o f flower showing departure o f whorl o f eight bundles; C, lower portion o f ovary showing abortion o f dorsal carpellary o f fertile carpel: D, base o f style showing commissural carpellaries and dorsal car pellary o f sterile carpel entering style, cc, commissural carpel lary; dc:, dorsal carpellary o f sterile carpel.Scale bar: 500 Jim.
, the only other worker who has discussed generic characters in the Thyme laeaceae, the following characters are generally of generic value: * the number of floral parts.* the point of insertion of the stamens and the dimen sion of their filaments which render them exserted or enclosed, * presence or absence of the scales in the throat of the hypanthium, * presence or absence of a disc at the base of the gynoecium, * whether the base of the hypanthium is shed or persists growing around the ripe fruit, and * the arrangement of the inflorescence.

TABLE 3 .-Size range of pollen grains (mean followed by range in parentheses) in Lachnaea and Cryptadenia Taxon Collector Diameter (|im)
species and sometimes even within individual species of Lachnaea and Cryptadenia.The variation range within Cryptadenia is smaller than in Lachnaea but one must take into account that Cryptadenia is a much smaller group of species.With regard to the habit, phyllotaxis and